Settlement and infrastructure vulnerability assessment due to land subsidence Geomorphological hazard in part of South Tehran

Vulnerability is a logical effect because of the risk of living in hazardous regions and determines the amount of endurablity of the capacity of risk and regeneration. Vulnerability is a complex phenomenon which includes environmental، political and economic-social divisions. According to subsidence risk generation in settlement areas and constructions in Tehran، the risk due to its morphological effects is trivial and it’s necessary to analyze and grade it. Unfortunately because of the missing of the knowledge about this phenomena by the at risk groups and disability to regulate it، the vulnerability includes a wide range involving economic-social and environmental fundamentals. Knowledge about the amount and range of vulnerability in this region can be a proper data base for managers and agents who are working to regulate، control and prevention of disaster. Study area: The study area includes the lands at high risk of subsidence in southern Tehran The approximate area of 64 square kilometers in area 17، 18، 19، and 20 in Tehran taken And mathematical the Is location of east longitude35̊ 35ʹ22ʺ up to 35̊ 39ʹ 39ʺand north latitude 51̊ 22ʹ 92ʺ up to 51̊ 18ʹ 19ʺ. These for study were the following Data: - ENVISAT Satellite radar images of the sensor ASAR the 45-day period in the spring and summer of 2011- Optical satellite images from Landsat TM sensor patch 164 Row 35 On 18/07/2010- The survey data collected from field operations with D-GPS- Documents and reports and library resourcesTherefore، by using of interferometry of radar waves، the rate and value of the subsidence in the studied area have been extracted. Then for generation of the map of the high risk areas، rate and value of subsidence، as an effective factor، delivered to analyzer system in GIS environment. The resulted map involves the cells of the different risk generation factor. In order to evaluation of the vulnerability، spatial distribution pattern of the buildings and the map of the vulnerable areas is considered. according to these information and by using of the field studying the vulnerability of the population، houses and buildings placed in the studied area is considered. Result and discussion، Knowledge of population and human groups’ vulnerability as a tool for prevention of expansion of living in hazardous regions is noticeable. Analysis of vulnerability of population centers which are stored in hazardous regions is a scientific action for providing a proper information basis of vulnerable degree of the risk Occurrence. According to such point of view the analysis of the vulnerability due to geomorphological subsidence hazards in the south of Tehran is noticeable. Extraction of the vulnerable areas showed that 12. 7% of the total area is the most vulnerable، 14. 7% of the total area is the vulnerable، 15. 5% of the total area is with a little risk and more than half (57%) of the area placed in the lower risk. the results proved that the most of the settlements and the related populations are vulnerable. The field studying showed that the most of the buildings are non-engineered which causes that the under construction buildings in the risk.